Can clang-format tell me if formatting changes are necessary?

Is there an way that you can run

clang-format

in a mode where it reports if the file meets the specified format? A kind of dry-run mode where it reports if a change is needed, but doesn't make the change. Ideally I'd like clang-format to just return a non-zero exit code if the file needs changes. Or, even more ideally, a non-zero exit code and a list of the files that need changes on standard output.

I'm trying to keep the question generic, so that more people can answer, but what I am trying to do is write a git pre-commit hook that will reject any commits that don't match the expected .clang-format . It's easy to run clang-format on the list of files in the index. But it's hard to know if clang-format actually changed anything.

I have one potential solution based on

-output-replacements-xml

(that I will post as an answer), but it's a hack and I feel like this should be more straightforward. Comments/suggestions, edits, different answers/approaches are all welcome.

One of the reasons I feel like this should be easier than it is because -output-replacements-xml essentially gives me the answer that I want, it just doesn't give it to me in an easy to consume way. However, since the output if no replacements are needed is very predictable, parsing the output isn't too hard.